An ink jet recording head has nozzles, ink chambers, an ink supply system, an ink tank, and transducers; by generating pressure in the ink chambers using the transducers, ink particles are ejected from the nozzles, and characters or images are recorded on a recording medium such as paper.
For example, in well-known forms, the transducer is used a heat-generating element, or else a thin-plate-shaped piezoelectric element having the whole of one surface thereof bonded to the outer walls of an ink chamber. In the case that a piezoelectric element is used, a pulse-like voltage is applied to the piezoelectric element, thus bending the composite plate comprising the piezoelectric element and the outer walls of the ink chamber, and the displacement/pressure generated through the bending is transmitted to the inside of the ink chamber via the outer walls of the ink chamber.
A sectioned perspective view of a conventional multi-nozzle ink jet head 100 using piezoelectric elements is shown in FIG. 20. As shown in FIG. 20, the head 100 is constituted from a row of piezoelectric bodies 111, individual electrodes 112 formed on the piezoelectric bodies, a nozzle plate 114 in which are provided nozzles 113, ink chamber walls 117 made of a metal or a resin that, along with the nozzle plate 114, form ink chambers 115 corresponding respectively to the nozzles 113, and a diaphragm 116.
A nozzle 113 and a piezoelectric body 111 are provided for each ink chamber 115, and the periphery of each ink chamber 115 and the periphery of the corresponding diaphragm 116 are connected together strongly. A piezoelectric body 111 for which a voltage has been applied to the individual electrode 112 deforms the corresponding part of the diaphragm 116 as shown by the dashed lines in the drawing. As a result, an ink drop is ejected from the nozzle 113.
Application of voltages to each of the piezoelectric bodies 111 is carried out separately using electrical signals from a printing apparatus main body via printed circuit boards. FIG. 21 is a drawing showing the constitution of connections between the conventional head and the printed circuit boards. In the example of FIG. 21, the head 100 has 8 rows and 8 columns of nozzles 113, i.e. of piezoelectric bodies 111 and individual electrodes 112. Corresponding to this, flexible printed circuit boards 110 are provided for connecting the driver circuitry of the apparatus to the individual electrodes 112.
In this prior art, the individual electrodes 112 are connected to the terminals of the printed circuit boards 110 by wires 120 through wire bonding. Moreover, art in which an FPC wiring board is connected directly is also known.
Moving on, due to demands to increase printing resolution, there are demands to increase the density of the nozzle arrangement on heads. If the nozzle density is raised, then the contact spacing between terminals (internal electrodes) is reduced. For example, the nozzle density of a head using piezoelectric bodies is currently about 150 dpi, but is advancing to 180 to 300 dpi, and further to 360 dpi, and hence the contact spacing is becoming lower.
However, currently the best contact spacing with wire bonding using semiconductor manufacturing is 150 dpi, with 300 dpi contacts being developed in the case of FPC connection. If electrical connection is carried out by providing contacts on top of or near to the piezoelectric bodies 111 as conventionally, then a problem of joining of neighboring contacts (shorting) may arise. Moreover, when connecting a large number of points in a short time, the load on the piezoelectric bodies 111 becomes very high, and with thin-film piezoelectric bodies there is a risk of breakage, and hence connection is extremely problematic.
Moreover, wire bonding requires about 1 second per point, and hence if the number of points rises due to increasing the density, then the manufacturing time increases, leading to an increase in cost. For example, with the example of FIG. 19, there are 48 points, and hence 48 seconds would be required. Furthermore, even in the case of FPC connection, it is necessary to connect the FPC to a printed circuit board having the driving circuitry thereon, and hence it is difficult to reduce the cost.